The firmware isn't operational so the cart's useless by itself right now. You'll need another flash cart to launch the update program on, then swap it out to stick your damaged cart in the slot and tell it to start applying the update. This trick only works on the DS/Lite, so if you have a DSi/3DS handy, remember they won't work.

If you're looking for a new one, check this, just updated it today to trim it down.
http://gbatemp.net/t290097-which-flash-cart-should-i-get

If you just want a cheap cart to start the update with to fix your current, the original R4 would work on the DS Lite.